Posted by: PercyUK
« on: July 21, 2020, 09:40:42 AM »Hi everyone, I just thought that I would let you know about what may be a quick fix for some of you who may be having trouble if your gearbox is grinding.
If this has been covered elsewhere then please forgive me.
On my T90 the shift lever (gear lever in the UK) was very sloppy. I found that most of the time when trying to take second gear on my rebuilt box I ended up grinding the gears.
I was happy that the synchro was working as it went from 2nd to 3rd without fault so I took the top off to explore.
As you know there is a metal ball on the lever which sits inside the top of the tower. This ball has a slot in it that engages with a pin. This pin should allow the lever to go backwards and forwards and side to side however due to excessive wear mine also was able to rotate a few degrees perhaps 5 or 10 at the most.
At the bottom of the lever is a square block that engages with the shift rails. There is not much space between the two rails and when I allowed mine to twist or turn it was in contact with both and there was a large scour in one rod as evidence of this occurring a lot in the past.
I suspect that without realising it I was twisting the lever as I went for second gear and it was getting trapped between the rods and causing problems.
My solution was simple.
I identified the most worn side of the slot in the ball and welding it with a Mig.
A Tig would have been easier but it still worked.
I then used a small end mill in my lathe to cut the weld back to produce a new edge to the slot and getting it close to original size.
You could easily do this by hand with a file and if you get it wrong simply weld it again and restart.
The result is now a much tighter lever with no twist and two quick tests up the road have so far proved positive for gear changes without grinding.
I know that there are many reasons why these boxes can cause problems but I would at least consider checking this before going to the trouble of a rebuild, if only to get a couple of more years out of it before you do so.
Hope this helps someone.
Cheers
Percy